The prostitutes of Kasungu, a rural corner of Malawi, are not amused. These days the farmers who once frittered away the proceeds of their harvests on them are to be found queuing to deposit cash at a bank under the watchful eyes of their wives.

An outbreak of fidelity does not, however, appear to explain why Kasungu’s brothels are empty. Instead, they blame the introduction of savings accounts for people previously considered “unbankable”.